This invention relates to a cover for enclosing a chamber and its contents in a fluid-tight seal. More particularly, it relates to a cover comprised of at least three individual layers bonded together. This invention also relates to a fluid-tight vessel comprising the present novel cover and a chamber provided with an opening therefor formed with an upstanding lip defining the perimeter of the opening. Under externally applied pressure, the cover is able to form and maintain a resilient, fluid-tight seal with the rigid upstanding lip. This cover and the vessel employing this cover are suitable for a wide variety of uses where a fluid-tight seal for enclosing a chamber is required, particularly when contents of the chamber are to be subjected to vigorous fluid processing, extremes of heat, pressure and harsh chemicals while the fluid-tight seal on the chamber is maintained. The present cover and the vessel employing it are especially suited for such procedures as acid processing of substrates.
It is often necessary to conduct various industrial or laboratory fluid treatment procedures in a vessel which must be maintained in a secure and absolutely fluid-tight seal, often while procedures are being carried out therein involving the use of high speed rotating or revolving parts and extreme agitation, mixing or spraying of chemical fluids in all directions within the sealed vessel. For example, in the manufacturing of integrated circuits, the wafers or substrates from which the chips are cut are processed through various steps, including etching, cleaning, acid processing and the like, wherein the wafers or substrates are supported in a chamber which must be enclosed in a fluid-tight seal prior to initiating the required procedure.
Previously available technology achieves a fluid-tight seal between the cover and the chamber by using such arrangements as a precision fit lid, a rubber gasket, or an O-ring around the edge of the chamber. In the processing of wafers or substrates, after the particular fluid treatment procedure has been completed, it is necessary to dry the wafers or substrates to total dryness, usually by draining and vacuum aspiration of the fluid contents of the chamber, prior to releasing the fluid-tight seal and opening the chamber. Using the previously available means of achieving a fluid-tight seal, a ring of fluid often penetrated to the area between the lip of the chamber and the cover, where it remained resistant to drying procedures. Upon opening the chamber, this residual ring of fluid tended to recondense on the wafers or substrates, adversely affecting their condition and readiness for further processing steps.